Ratchet drive mechanism



Nov. 9, 1965 H. E. GREENHOW 3,215,553

RATCHET DRIVE MECHANISM Filed Jan. 28, 1964 INVENTOR. HENRY E. GREEN HOW ATTORNEYS United States Patent 3,216,658 RATCHET DRIVE MECHANISM Henry E. Greenhow, Chingford, London, England, as-

signor to Veeder-Root Incorporated, Hartford, Conn., a corporation of Connecticut Filed Jan. 28, 1964, Ser. No. 340,720 13 Claims. (Cl. 23591) The present invention relates to a ratchet drive mechanism having notable utility in connection with the driving of a counter.

It is a principal aim of the present invention to provide a new and improved ratchet drive mechanism for translating oscillatory angular motion into unidirectional angular mot-ion which is particularly useful in a rela tively low torque drive as, for example, for driving a conventional multiple wheel counter and which can be economically and compactly constructed without jeopardizing reliability.

It is another aim of the present invention to provide an improved counter driving mechanism which provides a positive unidirectional drive of the counter and which precludes double counting and miscounting even at high driving speeds.

It is another aim of the present invention to provide a new and improved ratchet mechanism that can be installed for providing a unidirectional angular output in either angular direction.

It is a further aim of the present invention to provide a counter drive mechanism for translating an oscillatory angular motion into a unilateral stepping drive of the lowest order counter wheel and which can be compactly assembled with the counter and where desirable substant-ially within the usual annular rim of the lowest order wheel.

Other objects will be in part obvious and in part pointed out more in detail hereinafter.

The invention accordingly consists in the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereafter set forth, and the scope of the application of which will be indicated in the appended claims.

In the drawings:

FIG. 1 is a longitudinal side view, partly broken away and partly in section, of a rotary counting device incorpora ting the ratchet drive mechanism of the present invention;

FIG. 2. is a transverse section view of the counting device taken substantially along the line 2-2 of FIG. 1, and showing the ratchet drive mechanism in one operative position;

FIG. 3 is a transverse section view of the counting device. taken substantially along the line 33 of FIG. 1; and

FIG. 4 is a partial transverse section View of the counting device taken substantially along the line 2-2 of FIG. 1 and showing the ratchet drive mechanism in another operative position.

Referring now to the drawings in detail, a preferred embodiment of the ratchet drive mechanism of the present invention is installed for driving a counter having the usual coaxial number wheels of increasing order including a units wheel 12, a tens wheel 14, a hundreds wheel 16 and a thousands wheel 18. These wheels are freely mounted on a counter drive shaft 20 rotatably mounted in side plates 22, 24 of the counter frame, which frame additionally includes an elongated piece 26 secured to the end plates 22, 24 remote from the counter drive shaft 20. In a well-known manner the number Wheels 14, 16, 18 are indexed for each revolution of the next adjacent lower order wheels 12, 14, 16, respectively,

ice

by transfer pinions 28 only generally shown in FIG. 1, which are freely mounted on a transfer pinion shaft 30 extending between the side plates 22, 24.

In accordance with the present invention, the drive shaft 20 is adapted to index the units wheel 12 one indicia, for example, 36 degrees where, as in the conventional counter, the number wheel bears the sequence of indicia of 0-9. In the illustrated embodiment the drive shaft 20 drives or indexes the units wheel 12, in the counterclockwise direction as seen in FIG. 2, with a stop plate 34 being secured to the drive shaft 20 for limiting the angular displacement of the drive shaft to 36 degrees. The stop plate 34 is connected to the drive shaft by a pin 36 extending through a transverse opening in the shaft and received within a cooperating slot 38 in the stop plate, the pin 36 thereby additionally maintaining the stop plate against axial displacement on the shaft in one direction, to the right as seen in FIG. 1. The stop plate 34 is provided with a pair of stop shoulders 40, 42 (FIG. 3) which are adapted to engage the transfer pinion shaft 30 and thereby limit the angular freedom of movement of the drive shaft 20 to approximately 36 degrees. For returning the shaft 20 to an initial position after it has been angularly displaced for indexing the units wheel, there is provided a helical torsion spring 44 having one end encircling the transfer pinion shaft 30 and the other end encircling a pin 46 formed integrally with the stop plate 34. As a result, the torsion spring is adapted to urge the stop plate 34 and therefore the shaft 20 toward their initial position shown in FIG. 3.

The new and improved ratchet drive mechanism of the/present invention is-shown for op'eratively connecting the drive shaft 20 with the units number wheel 12. This mechanism includes a drive ratchet wheel 50 which is shown entirely received within an axially extending annular flange or rim 52 of the units wheel 12. The drive ratchet wheel 50 is driven by the shaft 20 through a pin 54' and a cooperating slot 56 in the hub 58 of the drive ratchet wheel similar to the driving connection between the drive shaft and stop plate 34. The hub 58 provides a transverse bearing face engageable by the units wheel 12 and the transverse pin 54 provides for retaining the drive ratchet wheel 50 against axial movement in one direction, to the left as seen in FIG. 1.

A reaction ratchet wheel 60 is mounted on the shaft 20 coaxially with the drive ratchet wheel 50 and intermediate the drive ratchet wheel and the stop plate 34. The reaction ratchet wheel 60 is shown to be nonrotatable, for which purpose there is provided a slot recess 62 in a radial extension of the reaction wheel for receiving the transfer pinion shaft 30. Intermediate the drive ratchet wheel 50 and the reaction ratchet wheel 6% is an elongated ratchet slide 66 constructed with a central elongated slot 68 for receiving the drive shaft 20 and thereby allow radial and rotational movement of the slide. The slide and ratchet wheels are preferably of molded plastic with the slide being of generally planar shape with opposed bearing surfaces engageable with the hubs of the ratchet wheels whereby the frictional resistance against radial and rotational movement of the slide is minimized.

As seen in FIG. 2, the annular rim S2 of the units wheel 12 is provided with two pairs of diametrically opposed radial slots 70, 72 which are preferably angularly spaced, substantially 90 degrees. The pair of slots 70 slidingly receive the longitudinal ends 71 of the ratchet slide and thereby provide an operative connection between the slide and units wheel 12 for driving the wheel. The pair of'slots 72 slidingly receive a pair of oppositely extending generally radial arms 74 molded integrally with-the slide and which thereby provide a resilient bias 3 for urging the slide to a neutral or rest position shown in FIG. 2.

Adjacent the longitudinal ends 71 of the slide 66 are a pair of oppositely extending axial projections or pawls 76, 78 which are adapted to cooperate with the drive and stationary ratchet wheels 50, 60, respectively. Cooperating with these pawls, 76, 78 are a plurality of peripheral teeth 80, 81 angularly spaced on the opposing faces of the drive and reaction ratchet wheels 50, 60, respectively. In the illustrated embodiment there are ten teeth 80, 81 on each wheel with the teeth being identical and with each tooth being symmetrical about its radial center line. Adjacent teeth on each wheel have substantially parallel opposed edges 82, 83-and 84, 85 for slidingly receiving the corresponding substantially parallel edges of the slide pawls 76, 78, respectively. Accordingly, the slide pawl 76 is adapted for radial reciprocable movement between the teeth 80 of the drive ratchet wheel 50 and the slide pawl 78 is adapted for similar reciprocable movement between the teeth 81 of the reaction ratchet wheel 60 whereby with the slide pawls in a radial position engageable with the teeth of the corresponding wheel there is provided an operative connection between the slide and that wheel.

For radially reciprocating the slide 66 from its neutral or rest position (FIG. 2) to which the slide is urged by the resilient arms 74, the pawls 76, 78 are provided with generally inwardly facing cam edges 86, 87 shown to be parallel and inclined to the diametral center line of the opposed pawls at an angle of approximately 65 degrees. With the slide in its neutral position the camming edges extend from a point within the periphery of the ratchet wheel teeth 80, 81 to a point radially outwardly of the teeth. Accordingly, with the slide in its neutral position both of the pawls 76, 78 have operative engagement with their corresponding ratchet wheels. As a result, when the drive shaft 20, and consequently the drive ratchet wheel 50, is angularly displaced in the driving direction, counterclockwise as seen in FIG. 2, one of the teeth 80 on the drive ratchet wheel abuts the slide pawl 76 to angularly displace the slide and therefore the units wheel 12 in conjunction with the displacement of the drive shaft. During this forward angular displacement of the slide the camming edge 87 of the slide pawl 78 engages a tooth 81 on the reaction ratchet wheel to radially displace the pawl 78 outwardly of the reaction wheel teeth, as best seen in FIG. 4. After 36 degrees of angular displacement of the slide 66, the pawl 78 will be free to move inwardly under the bias of the resilient arms 74 to its neutral position.

With the returning movement of the drive shaft 20, clockwise as seen in FIG. 2, the slide pawl 76 is radially displaced out of operative engagement with the teeth of the drive ratchet wheel and the slide pawl 78 is maintained in engagement with the teeth of the reaction ratchet wheel to prevent angular displacement of the slide and therefore the counter wheel 12. Again, after the shaft has returned a full 36 degrees the resilient arms 74 move the slide inwardly to its neutral position thereby conditioning the ratchet mechanism for a subsequent indexing cycle.

With the ratchet mechanism installed as shown in the drawings, the units wheel 12 is driven in the counterclockwise direction as seen in FIG. 2. However, the units wheel 12 and consequently the entire counter can be driven in the opposite angular direction by merely inverting the slide plate 66 with the slide pawl 78 positioned for coacting with the teeth of the drive ratchet wheel 50 and with the slide pawl 76 positioned for coacting with the teeth of the reaction ratchet wheel 60. With the slide in such an inverted position with respect to that shown in the drawings, the cam edges 86, 87 of the slide pawls will face in the opposite angular direction. As a result, when the drive shaft 20 is angularly displaced, in the clockwise direction as seen in FIG. 2, the slide pawl 78 will coact with the teeth of the drive ratchet pawl to drive the units wheel in the clockwise direction, and when the drive shaft is angularly displaced, in the counterclockwise direction as seen in FIG. 2, the slide plate 66 and therefore the units wheel will remain stationary. For such reverse operation of the counter the position of the torsion spring may be reversed to provide a counterclockwise bias on the drive shaft, as seen in FIG. 3, for which purpose the pin 46 is angularly positioned intermediate the shoulder stops 40, 42 to allow for installation of the torsion spring in either reverse position.

Of course the drive ratchet wheel 50 and the stop plate 34 are to be related on the shaft 20 so that the teeth 80, 81 are in substantial alignment when the drive ratchet wheel is at its extreme angular positions in its oscillatory cycle so as to allow the slide to assume its neutral position at these extreme angular positions. However, inasmuch as the slide pawls 76, 78 have several degrees of freedom with respect to their coacting ratchet wheels when the slide is in its neutral position, there is a tolerance of several degrees in the alignment of the teeth of the ratchet wheels when the drive ratchet wheel is in its extreme position.

Thus it can be seen that the ratchet drive mechanism of the present invention has notable usefulness in connection with the driving of a conventional counter, particularly where compactness, economy and reliability are desired. Additionally, the ratchet drive mechanism is positive and precludes double counting or miscounting even when the counter is driven at high speeds. Moreover, when the ratchet drive mechanism is used Without means limiting the angular freedom of movement of the drive shaft or drive ratchet wheel, the mechanism can be usefully employed as a unidirectional rotary drive mechanism which precludes reverse rotary motion of the output. Further, the ratchet drive is capable of providing a unidirectional angular output in either angular direction by appropriate installation of the reciprocable ratchet slide.

As will be apparent to persons skilled in the art, various modifications and adaptations of the structure above described will become readily apparent without departure from the spirit and scope of the invention, the scope of which is defined in the appended claims.

I claim:

1. A ratchet mechanism for providing a unidirectional angular drive comprising a drive ratchet wheel, a nonrotatable reaction ratchet wheel coaxial with the drive ratchet wheel, a rotary output member coaxial with the drive and reaction ratchet wheels, and a driven ratchet slide radially reciprocable between a drive position in operative engagement with the drive ratchet wheel and a reaction position in operative engagement with the reaction ratchet wheel, slide mounting means providing a driving connection between the radially reciprocable slide and the rotary output member and biasing the slide to a radial position intermediate its drive and reaction positions, said ratchet slide and ratchet wheels having coacting means with the slide in its said intermediate radial position moving the slide ratchet radially to its drive position upon movement of the drive ratchet wheel in a driving angular direction and moving the ratchet slide radially to its reaction position upon movement of the drive ratchet wheel in the opposite angular direction.

2. A ratchet mechanism for providing a unidirectional angular drive comprising a rotary output member, a drive ratchet wheel coaxial with the output member, a nonrotatable reaction ratchet wheel coaxial with the drive ratchet wheel, said drive and reaction ratchet wheels having a plurality of angularly spaced teeth thereon, and a ratchet slide radially reciprocable intermediate the drive and reaction wheels between a drive position in abutment with a tooth of the drive ratchet wheel only and a reaction position in abutment with a tooth of the reaction ratchet wheel only, drive means providing a drivingconnection between the rotary output member and the ratchet slide, resilient means for urging the slide to a radial position intermediate its drive and reaction positions, said ratchet slide and ratchet wheels coacting with the slide in its said intermediate radial position to move the ratchet slide to its drive position upon movement of the drive ratchet wheel in a driving angular direction and to move the ratchet slide to its reaction position upon movement of the drive ratchet wheel in the opposite angular direction.

3. A ratchet mechanism for providing a unidirectional angular drive comprising a rotary output member, a drive ratchet wheel coaxial with the output member, a non-rotatable reaction ratchet Wheel coaxial with the drive ratchet wheel, said drive and reaction ratchet wheels having a plurality of angularly spaced teeth thereon, and a ratchet slide radially reciprocable intermediate the drive and reaction wheels between a drive position in abutment with a tooth of the drive ratchet wheel only and a reaction position in abutment with a tooth of the reaction ratchet wheel only, said ratchet slide and ratchet wheels coacting to move the ratchet slide to its drive position upon movement of the drive ratchet wheel in a driving angular direction and to move the ratchet slide to its reaction position upon movement of the drive ratchet wheel in the opposite angular direction, said rotary output member having an annular rim and said ratchet slide having a pair of oppositely extending resilient radial arms connected to the annular rim for biasing the ratchet slide to a radial position intermediate its driving and reaction positions.

4. A ratchet mechanism for a unidirectional angular drive comprising a drive ratchet wheel, a non-rotatable reaction ratchet wheel coaxial with the drive ratchet wheel, said drive and reaction ratchet wheels having opposed faces with a plurality of axially extending teeth thereon angularly spaced to define generally radial slots therebetween, and a drive ratchet slide radially reciprocable intermediate the drive and reaction ratchet wheels between a drive position engageable with a tooth of the drive ratchet wheel and a reaction position engageable with a tooth of the reaction ratchet wheel, said ratchet slide and ratchet wheels coacting to move the ratchet slide to its drive position upon movement of the drive ratchet wheel in a driving angular direction and to move the ratchet slide to its reaction position upon movement of the drive ratchet wheel in the opposite angular direction.

5. A ratchet drive for translating oscillatory angular motion into unidirectional angular motion comprising a drive ratchet wheel adapted for angular oscillation in driving and returning angular directions, a nonrotatable reaction ratchet wheel coaxial with the drive ratchet wheel, said drive and reaction ratchet wheels having opposed faces with a plurality of axially extending teeth thereon angularly spaced to provide generally radial slots therebetween, and a driven ratchet slide radially reciprocable intermediate the drive and reaction ratchet wheels between a drive position engageable with a tooth of the drive ratchet wheel and a reaction position engageable with a tooth of the reaction ratchet wheel, said ratchet slide having a pair of diametrically opposed camming edges engageable with the teeth of the drive and reaction ratchet Wheels respectively to move the :slide to its drive position upon movement of the drive ratchet wheel in a driving angular direction and to move the slide to its reaction position upon movement of the drive ratchet wheel in a returning angular direction.

6. A ratchet drive for translating oscillatory angular motion into unidirectional angular motion comprising a drive ratchet wheel adapted for angular oscillation in driving and returning angular directions, a nonrotatable reaction ratchet wheel coaxial with the drive ratchet wheel, said drive and reaction ratchet wheels having angularly spaced teeth thereon, a driven ratchet slide radially reciprocable intermediate the drive and reaction ratchet wheels having a pair of diametrically opposed axially extending pawls adapted for engagement with the teeth of the drive and reaction ratchet wheels respectively, said ratchet slide being radially reciprocable between a drive position with one of the pawls engageable with a tooth of the drive ratchet wheel and a reaction position with the other of the pawls engageable with a tooth of the reaction ratchet wheel, said ratchet slide having a radial position intermediate said drive and reaction positions with said one and said other pawl engageable with teeth on the drive and reaction ratchet wheels respectively, and means urging the ratchet slide to its intermediate position.

7. A ratchet drive for translating oscillatory angular motion into unidirectional angular motion comprising a drive ratchet wheel adapted for angular oscillation in driving and returning angular directions, a nonrotatable reaction ratchet wheel coaxial with the drive ratchet wheel, said drive and reaction ratchet Wheels having opposed faces with a plurality of axially extending angularly spaced teeth thereon, said teeth having oppositely facing generally radially extending edges with the opposed edges of adjacent teeth being angularly spaced to define radial slots therebetween, a driven ratchet slide radially reciprocable intermediate the drive and reaction ratchet wheels between a drive position engageable with a tooth edge of the drive ratchet Wheel and a reaction position engageable with a tooth edge of the reaction ratchet wheel, said ratchet slide having a pair of diametrically opposed axially extending drive pawls adapted for being slidingly received within said slots for engagement with the tooth edges, said pawls having inwardly facing generally parallel cam edges having an inclination of less than to the diametral center line of the opposed pawls.

8. The ratchet drive of claim 7 further comprising means biasing the ratchet slide to a radial position intermediate its drive and reaction positions.

9. The ratchet drive of claim 7 further comprising a rotary output member coaxial with the ratchet wheels having an annular rim with diametrically opposed radial slots slidingly receiving the ratchet slide.

10. A ratchet mechanism for providing unidirectional angular drive comprising a drive shaft, a rotary output member freely mounted on the drive shaft having a rim, a drive ratchet wheel mounted on the drive shaft for movement therewith and within the rim, a non-rotatable reaction ratchet wheel mounted coaxially with the drive ratchet wheel, and an elongated ratchet slide plate intermediate the ratchet wheels having -a longitudinally extending central slot receiving the drive shaft, said drive and reaction ratchet wheels having axially extending hubs engageable with the slide plate and a plurality of angularly spaced teeth thereon, said ratchet slide plate having a pair of diametrically opposed axial projections providing pawls adapted for abutting engagement with the teeth of the drive and reaction ratchet wheels respectively, said rim having a first pair of diametrically opposed radial slots receiving the ratchet slide plate to provide a driving connection therebetween, said rim having a second pair of diametrically opposed radial slots and said slide plate having a pair of laterally extending resilient arms received in the second pair of radial slots.

11. In a counting device comprising a drive shaft adapted for oscillation in counting and returning angular directions, a number wheel freely mounted on the drive shaft having an axially extending annular flange, a drive ratchet wheel mounted on the drive shaft for oscillation therewith and within the annular flange of the number wheel, a nonrotatable reaction ratchet wheel coaxially mounted with the drive ratchet wheel, said drive and reaction ratchet wheels having a plurality of angularly spaced teeth, and a ratchet element intermediate the ratchet wheels operatively connected for driving the number wheel in a counting angular direction upon oscillation of the drive shaft, the improvement wherein the ratchet element is a ratchet slide intermediate the ratchet wheels having a pair of diametrically opposed pawls adapted for abutting engagement with the teeth of the drive and reaction ratchet wheels respectively, wherein the number wheel flange is provided with diametrically opposed radial slots receiving the slide for radial reciprocation between a drive position with one of the pawls in abutment with a tooth on the drive ratchet wheel and a reaction position with the other of the pawls in abutment with a tooth on the reaction ratchet wheel, and wherein the teeth on the drive and reaction wheels and the pawls coact to cam the ratchet slide to its drive position upon angular movement of the shaft in the driving direction and to cam the ratchet slide to its reaction position upon angular movement of the shaft in the returning direct-ion.

12. The improvement of claim 11 wherein there are ten teenth on each of the ratchet wheels.

13. In a counting device comprising a drive shaft adapted for a oscillation in counting and returning angular directions, a plurality of number wheels of ascending order freely mounted on the drive shaft, transfermeans between the number wheels, a drive ratchet wheel connected tothe drive shaft, a nonrotatable reaction ratchet wheel coaxial with the drive ratchet wheel, and a ratchet element intermediate the ratchet wheels operatively connected for driving the lowest order number wheel in a counting angular direction upon oscillation of the drive shaft, the improvement wherein the ratchet element is a ratchet slide connected to the lowest order number wheel and radially reciprocable between a drive position in operative engagement with the drive ratchet wheel and a reaction position in operative engagement with the reaction ratchet wheel, and wherein the slide pawl and the ratchet wheels have coacting means moving the slide pawl radially to its drive position upon movement of the drive shaft in its counting direction and moving the slide pawl to its reaction position upon movement of the drive shaft in its returning direction.

References Cited by the Examiner UNITED STATES PATENTS LEO SMILOW, Primary Examiner. 

10. A RATCHET MECHANISM FOR PROVIDING UNIDIRECTIONAL ANGULAR DRIVE COMPRISING A DRIVE SHAFT, A ROTARY OUTPUT MEMBER FREELY MOUNTED ON THE DRIVE SHAFT HAVING A RIM, A DRIVE RATCHET WHEEL MOUNTED ON THE DRIVE SHAFT FOR MOVEMENT THEREWITH AND WITHIN THE RIM, A NON-ROTATABLE REACTION RATCHET WHEEL MOUNTED COAXIALLY WITH THE DRIVE RATCHET WHEEL, AND AN ELONGATED RATCHET SLIDE PLATE INTERMEDIATE THE RATCHET WHEELS HAVING A LONGITUDINALLY EXTENDING CENTRAL SLOT RECEIVING THE DRIVE SHAFT, SAID DRIVE AND REACTION RATCHET WHEELS HAVING AXIALLY EXTENDING HUBS ENGAGEABLE WITH THE SLIDE PLATE AND A PLURALITY OF ANGULARLY SPACED TEETH THEREON, SAID RATCHET SLIDE PLATE HAVING A PAIR OF DIAMETRICALLY OPPOSED AXIAL PROJECTIONS PROVIDING PAWLS ADAPTED FOR ABUTTING ENGAGEMENT WITH THE TEETH OF THE DRIVE AND REACTION RATCHET WHEELS RESPECTIVELY, SAID RIM HAVING A FIRST PAIR OF DIAMETRICALLY OPPOSED RADIAL SLOTS RECEIVING THE RATCHET SLIDE PLATE TO PROVIDE A DRIVING CONNECTION THEREBETWEEN, SAID RIM HAVING A SECOND PAIR OF DIAMETRICALLY OPPOSED RADIAL SLOTS AND SAID SLIDE PLATE HAVING A PAIR OF LATERALLY EXTENDING RESILIENT ARMS RECEIVED IN THE SECOND PAIR OF RADIAL SLOTS. 